The present invention relates to a method of and an arrangement for corona treatment of web-shaped materials or shaped bodies with the use of one or several corona electrodes, in which gases produced during the corona treatment in the operating region, such as for example ozone, nitrogen and the like, are aspirated.
It is known that the adhesion on surfaces of a material can be improved by the treatment with an electric corona discharge, or in the event of nonpolar material, the corona discharge provides for a respective adhesive surface. The corona discharge is formed through ozone which is produced during the discharge on the oxidative adhesive centers of the treated material surface. The intensity and number of the adhesive centers is correlated with utilized energy level and discharge frequency. The ozone which is generated during the discharge is extremely aggressive so that the operational personnel of the arrangements for corona treatment must be reliably protected from this ozone. This is carried out by aspiration of the ozone in the region of the corona electrode.
It has been shown that the ozone aspiration results in a reduction of the efficiency of the corona treatment. Especially in the event of big production installations with respective power output and correspondingly big corona discharge installations, this is a very negative factor. The ozone aspiration which has been performed in known arrangements has a further disadvantage in that the electrically relatively conductive ozone as undesirable ionization medium for the corona ignition is only partially available. The same is true with respect to relative electrically conductive nitrogen which is also produced during a corona treatment and becomes no longer available after the aspiration as waste product of the production process.
It is also known that the corona discharge is favorably influenced when the operating region of the high voltage corona electrode is supplied with noble gases such as argon, neon, helium and the like. Since these noble gases or noble gas-containing gas mixtures are very expensive, their use has certain limits with respect to their effective optimization.
An especially unfavorable situation is in the area of the treatment of solvent-containing substrates. In this area, considerable apparatus - and control expenses must be provided because of an explosion danger, for preventing aspiration of igniting solvent/air mixture through the ozone aspiration on the corona electrode, on the one hand, and for preventing health-hazardous ozone on the working place, on the other hand.